End Effects in Linear Tubular Motors and Compensated Position Sensorless Control Based on Pulsating Voltage Injection

Abstract

The sensorless position control of permanent magnet synchronous motors can be successfully implemented by superimposing a high-frequency voltage signal on the control voltage. In this paper the position estimation is obtained by means of a high-frequency sinusoidal voltage signal injected along the estimated d-axis. Several methods proposed in the literature obtain the position estimation by tracking the zero condition of the high-frequency q current component. We propose a new approach that also exploits the d-axis high-frequency current component, allows working with injected voltage signal of reduced amplitude thus reducing noise and additional losses. The main contribution of paper relies in the compensation of the motor end-effects, due to the finite length of the tubular motor armature. These effects must be taken into account in the motor modeling because cause an error in the position estimation that is variable with the motor position. The modeling of the phenomenon and a proper compensation technique are proposed in the paper. Last, a simplified I-type controller is used to estimate motor position instead of the commonly adopted PI controller plus integrator and this requires a low-effort design. Experiments on a linear tubular permanent-magnet synchronous motor prototype are presented to validate the theoretical analysis and evidence the feasibility of the proposed sensorless technique. I.

Analysis and Minimization of Detent End Force in Linear Permanent Magnet Synchronous Machines

“…However, the detent force caused by the slot and end effects in LPMSMs will reduce the positioning accuracy, introduce the vibration and noise, and deteriorate the control characteristics [5]- [8]. Similar to the conventional rotary PMSMs, the slot effect can be minimized by using skewed PMs [9], [10], slot-opening shifting [11], [12], and appropriate slot/pole combination [13].…”

Detent Force Reduction of an Arc-Linear Permanent-Magnet Synchronous Motor by Using Compensation Windings

“…ECAUSE of its high velocity, no transmission, large force, wide travel range and rapid dynamic response characteristic, the permanent magnet (PM) linear synchronous motor (PMLSM) is more and more used in commercial, industrial, and military applications [1][2][3][4][5]. For some scanning system and radar system, a rotary motor with gear box is usually adopted to realize the limited angular movement, which brings some drawbacks, such as occupying large space, bringing transmission error and having low response performance.…”

No-Load Magnetic Field and Cogging Force Calculation in Linear Permanent-Magnet Synchronous Machines With Semiclosed Slots

“…INEAR permanent magnet (PM) synchronous machines (LPMSMs) can provide direct thrust force without the need of conversion from rotational torque to linear force, and thus are increasingly employed in various industrial and military applications, such as railway transportation, robotic systems and electromagnetic launchers [1][2][3][4][5]. Among various types of LPMSMs, the slotted topologies suffer from the slot and end effects which increase the thrust fluctuation and decrease the machine controllability.…”